Biodiversity in the garden

Jill Severn

Photo by Anna Schlecht

Bee-friendly gardens have been in the spotlight for the past several years, and now the focus has widened to focus on a bigger idea: biodiversity in our gardens.

The state’s Fish and Wildlife has a nifty Habitat at Home website. The current issue of Fine Gardening has an article extolling caterpillars as a keystone critter we should plant to preserve.

Then there’s my current garden hero, Fergus Garrett, head gardener at Great Dixter, the English estate of my dearly departed garden hero, Christopher Lloyd.

Garrett was persuaded by his ecologist wife Amanda to commission a biodiversity audit of Great Dixter’s six-acre public garden. His first toe in the water was to invite an arachnological society to hold a meeting in the 15^th-century house at the heart of the garden. The spider-lovers had believed that gardens were inhospitable to their eight-legged friends, but during their lunch hour, when they strolled around, they were thrilled to find, among many other species, a spider so rare a sighting of it hadn’t been recorded since 1905.

The full audit found over 2,600 species of wildlife in the garden, though I’m guessing that leaves out all the soil organisms and other microscopic life we rely on but don’t see.

What’s come of that biodiversity audit – and from Garrett’s effectiveness as an educator – is a shift in our growing awareness of how to garden with biodiversity in mind.

Another voice in this growing shift is Doug Tallamy, a conservationist, writer, professor, and cofounder of the Homegrown National Park movement. It proposes that if all gardeners focused on increasing biodiversity, our gardens could collectively outmatch the habitat value of all the nation’s national parks.

Much of this work is focused on supporting insects, which Tallamy regards as the essential base of the food web, now in mortal danger from human activity and climate change. There have been dire warnings of an “insect apocalypse,” though researchers differ about how dire it is.

Supporting wildlife and insect recovery would mean growing more native plants, but it doesn’t exclude non-natives with high value to pollinators and other insects. In fact, Tallamy says that some native plants provide little habitat value, and some non-natives provide a lot.

All creatures need food, water, shelter, and a place to raise their young – or, for some species, a place to stash their eggs or immature progeny where they can mature and survive on their own. But this is a complicated challenge.

For the average gardener who never took a course in entomology, this might require a winter of study about insects, other critters, and all their habitat needs. Then we’d need to discern what species to encourage and what the consequences would be. Few gardeners would be willing to devote ourselves to improving habitat for aphids – or for marauding slugs or deer. And beyond insects, we’d need to know more about what frogs, snakes, bats, birds, and the other critters we need.

But there are some things we already know: lawns are low habitat value, and fall and winter messiness are high value. There are bees that winter in the hollow stems of spent flowers and insect larvae that hang out in rotting leaves. And where are all the spiders stashing their egg cases?

All this brings to mind an extremely messy friend who once lived in a house with a yard so completely neglected that a huge shrub covered her bedroom window. She reported that a hummingbird nested in the shrub, and she got to watch its nest, with eggs the size of jelly beans and then watched the mother feed the hatchlings until they fledged. I envied her that experience and revised my opinion about garden chaos. I’ve also wondered what sort of shrub that was.

So yes, maybe we could all be rewarded with similar experiences if we invest some time this winter in learning more about which native and non-native plants support wildlife and how to make our gardens more biodiverse and a bit messier.

There is a lot of life going on in our gardens in winter, much of it hidden from view. Poking around in the messy places to see it can also be part of our education. I’m going to polish up my magnifying glass and see how many wild neighbors I can meet in the next few months.

Jill Severn writes from her home in Olympia, where she grows vegetables, flowers and a small flock of chickens. She loves conversation among gardeners. Start one by emailing her at  jill@theJOLTnews.com